Once he was not such a reclusive and angry man (I speak of Kea), he used to be merely cautious and stern. He could also see colors as vividly as the sun allowed. It took only one day, one moment, to change that.

Long ago Kea had a (human) friend, whose name I will not mention, that spent many a day with him. This man was from one of the Native peoples of our own (the Māori, as it were) and lived within the same tribe that Kea sought refuge in at the time. (His reasoning for seeking refuge is a story within itself, one that I will not be delving into presently). They spent many a year together and had become quite good friends with hardly anything to dispute of between them. With the exception of one thing: Kea's friend had a grudge. An enemy of his own from within an enemy tribe.

I will say for the sake of your understanding that both tribes fought occasionally and, while they were not bitter enemies, they had many a grudge against one another. This time, however, was one of peace between the two tribes. Now Kea's friend had a specific grudge against one man in particular within this enemy tribe. I will not mention his name either, but for the sake of clarity let us call Kea's friend Crow and this other man Dove.

Crow despised Dove, and would often try whatever he could to, as he once claimed, "get revenge on him." Crow did this for reasons unknown to me, as Kea will not speak of it nor will I ask, but they were apparently unjust reasons. As Dove had never truly wronged him. Crow, after finding out that Kea was a Tohunga mākutu (that is one who has the ability to cast spells upon others to make them sick or die), relentlessly asked him to help put a spell upon the man. To which Kea would deny every time.

One day Crow came running up to Kea covered in cuts, bruises, and blood. Kea was alarmed and Crow told him that he had spoken with the elders and finally made peace with Dove. But, when Crow went to ask for Dove's forgiveness at Crow's wrongdoings to him, Dove mercilessly beat him and told him that he would never be forgiven. Crow begged Kea not to do anything to Dove, as he stated he still wanted to make peace with him, but Kea became enraged.

Angered that Dove would attack someone trying to make peace with him, combined with the fact that Crow was a good friend of his, he wished nothing but justice to be given. He sent Crow back to one of the Clans of their tribe to be healed and then himself went out into the wilderness to begin his own giving of justice. He created a curse to put upon Dove, that he "may never again see any other color than the purest red, like that which flows through the veins, so that he may forever be reminded of his wicked deed."

There was one problem though, Dove had not done anything that Crow had said. In fact Crow had beat himself and made up the story, all just to get his unjust revenge on Dove. Little did he know that a curse would return to its caster threefold if used on an innocent (in some cases). I believe had Kea known he was being lied to from the beginning Crow would have received punishment for his actions. But that was not how things occurred afterwards.

After Kea had finished the curse and sent it forth, it returned to him and he lost the ability to see any color at all. Upon learning that he'd been tricked, Kea was devastated and angered once more. though this time his anger was towards his supposed friend, Crow, who had deceived him into casting a curse on an innocent man. Though Kea was unable to do anything about it as, unknown to him at the time, he had been watched as he laid the curse. He was cast out from the tribe he had called home and chased away for being a Wahine mākutu (what is referred to today as a witch or sorcerer/sorceress).

Kea has never forgotten what was done to him and still holds a grudge to this day (though he may deny it). He now refuses to let anyone close to him. I think it is because he is afraid that such an incident may happen again if he does. Though I have not asked and he has not told me. As it is a sensitive topic for him. He now also refuses to uses curses or spells against anyone unless is is certain that they are deserving of it. As much as he gripes, insults, complains, and is downright uncivil towards others he can truly find it within himself to care. Proven by the fact that he will sometimes take the form of a raven to warn others of danger or ill intent. But that is a story for another time.......

I guess the reason I have told you this story is perhaps because I think it unwise to judge someone by how they act or appear to be, for that is not always who they are, and you never know what they have gone through in their lives (especially the long lives of us nations!)
Or perhaps it was to warn you not to mention or bring up Kea's colorblindness, as that would be a very unwise thing if you value your limbs! (I speak from personal experience. Though as a nation, and magic user myself, I heal much faster and better than humans so if you are not a nation you might wish to be extra cautious of the subject...)
I am unsure myself as to my reasonings. But, whatever the case, I hope you take heed of the lesson this story brings: know exactly who are your friends and who are your foes, lest you make a dire mistake.     

[in case anyone was confused, it was Moana who was telling this story]